A stone is whirled in a horizontal circle on a string. If the string suddenly breaks, the stone will
Correct answer: B. move along the tangent to the circle at the point of release
- A. fly radially outwards from the centre
- B. move along the tangent to the circle at the point of release
- C. fall straight down at once
- D. spiral outwards while slowing down
Explanation
With the centripetal force gone, no force acts horizontally and Newton's first law takes over, so the stone keeps the velocity it had at that instant, which is directed along the tangent. Gravity then curves the path downwards into a projectile trajectory. The belief that it flies straight outwards comes from thinking of centrifugal force as real.
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About Angular and Linear Quantities
Rotational motion relates angular displacement, angular velocity and angular acceleration to linear displacement, tangential velocity and tangential acceleration through the radius. Questions use radians, v equals r omega and tangential acceleration, while distinguishing tangential velocity from centripetal acceleration and angular quantities from their linear counterparts.
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